What is a shuttles main engine powered by?

The Space Shuttle main engines are powered by a combination of Liquid Oxygen (LOX) as an oxidizer and Liquid Hydrogen (LH2) as a fuel. Both propellants are stored in the space shuttle's External Tank during launch. They are fed into the space shuttle's main engines by umbilical lines on the external tank, and then the orbiter's main propulsion system feed lines. The Space Shuttle's main engines can achieve a thrust level of about 512,300 pounds, which is greater than 12,000,000 horsepower.